Hole cutting tool and method

ABSTRACT

A tool and a method for cutting holes in a container wall such as in a tank, a cistern, a pipeline, a vehicle, a ship, a production like or the like that contains inflammable, explosive, or other hazardous gasses, and liquids. The tool includes means for pressurising a cutting medium and discharging said medium via a nozzle. The nozzle is arranged in an enclosing cover including a scalable safety outlet for evacuation of the container contents. The cover has means of sealed-off abutment against the container wall concerned in the area in which hole cutting is to be performed. The nozzle is arranged to be directed towards the container wall in such a way that in use the cutting medium is discharged in the form of a jet impinging against the container wall with sufficient force to cut through said wall.

TECHNICAL FIELD OF INVENTION

The present invention relates to a tool for cutting holes in containerwalls, such as in tanks, cisterns, reservoirs, pipelines, vehicles,boats, production lines or the like that contain inflammable, explosiveor other hazardous gases and liquids.

BACKGROUND OF THE INVENTION

In connection with accidents involving for example tank cars, gas tanks,cisterns, pipelines, production lines and the like it is often necessaryto evacuate their contents before normal safety measures can beinitiated. The work involved in the evacuation of inflammable, explosiveor other hazardous and perilous gases and liquids constitutes aconsiderable hazards both to persons actively taking part in the rescuework and to persons present in the immediate surroundings.

Rescue methods according to prior-art technology therefore often involvevacating people from the immediate surroundings, which could be quite anextensive operation in case the accident occurs for example in a denselypopulated area.

According to prior-art methods of evacuating gases and liquids fromcontainers the valves of which have become unserviceable or for someother reason cannot be used, a sleeve is welded onto the container wallso as to be tightly secured thereto. A valve is then mounted on thesleeve and an aperture is drilled through the valve and the containerwall with the aid of a special drill. The reason for attaching thesleeve by means of welding is to ensure that it can withstand the forcesexerted in the drilling operation. The sleeve, the valve, and the coversurrounding the drill usually are filled with nitrogen in order toreduce the risk of ignition by the heat generated in the drillingoperation. Hoses are connected to the valve, causing the contents toflow automatically or by suction into a fresh container, alternativelyto a flare for flaring. Today, the welding step as well as thesubsequent drilling step are at least partly effected manually, whichoften constitutes a danger to the lives of the persons involved,particularly if the containers hold explosive, poisonous or inflammablematerials and both steps are carried out under heat-release conditions.

Naturally, it is a serious problem that several steps of the evacuationwork according to prior-art technology need to be carried out in amanner endangering the lives of the workmen and therefore alsoconstituting a considerable risk of exposing the surrounding area tohazards. Consequently, there is a considerable need for a methodallowing containers holding dangerous material to be emptied in a lessrisky way, particularly in conjunction with clearance work occasioned byaccidents or the like. Since dangerous goods is transported also throughdensely populated areas, there is likewise a need for avoiding, as faras possible, situations that may lead to a large number of individualshaving to be vacated from the immediately surrounding area. This type ofoperations delay the rescue work proper and are both expensive andcomplex.

SUMMARY OF THE INVENTION

The main object of the present invention therefore is to provide asolution of evacuating gases or liquids, particularly dangerous orexplosives gases or liquids, that is safer than prior-art solutions.This purpose is achieved in accordance with the invention by means of amethod and a tool for cutting holes in constructions of the kindoutlined in the introduction.

With respect to the method, this main object is achieved by cutting bymeans of a pressurised cutting medium, which is sprayed during thecutting operation into the construction concerned in the form of acold-cutting jet issued from a nozzle encased in a cover placed insealed-off abutment against the container wall, from which, containerthe contents therein are discharged via a safety outlet. The methodmakes possible to effect the sealed-off application as well as the holecutting steps while using methods that do not involve any risk ofgeneration of sparks and other uncontrollable development of heat.

The hole-cutting tool possesses the characterising features appearingfrom the appended claim 1. Preferred embodiments of the hole-cuttingtool are defined in the dependent claims.

Thus, the invention also concerns a tool for cutting holes in a wall ofa container, such as e.g. a wall of a tank, a cistern, a reservoir, apipeline, a vehicle, a ship, a production line or the like, containinginflammable, explosive or other perilous gases and liquids, said toolcomprising means for pressurising a cutting medium and discharging saidmedium via a nozzle, at least the nozzle being arranged in an enclosingcover comprising a safety outlet for evacuation of the containercontents, and having means for sealed-off abutment against the containerwall concerned in the area in which the hole cutting is to be performed,said nozzle arranged to be directed towards the container wall in such away that in use the cutting medium is discharged in the form of a jetimpinging against the container wall with sufficient force to cutthrough said wall.

Because a cover is arranged around the hole-cutting equipment insealed-off abutment against the container wall, an encapsulated space iscreated in which the hole-cutting operation may be performed under safeand controllable conditions. The parts abutting against the containerwall are provided with seals. The seals are made from a porous or aresilient material, such as rubber. The tool is attached to thecontainer wall using such means as strapping, chains, wires or glue.Another method is to use vacuum.

Another advantage of the invention is that it allows test pressurisationprior to cutting the hole and the subsequent evacuation, in order tocheck whether these operations may be carried out in a safe way andconsequently the risks be minimised. Depending on thetest-pressurisation results and other circumstances connected with theaccident, the sealing arrangements may have to be improved further priorto the hole being cut. The improvement may involve for instance makingthe very means for tighter abutment more powerful or applying siliconebetween the seals.

In accordance with the teachings of the invention, the hole-cutting toolis formed with an arm, which carries the nozzle for rotary motion abouta shaft. Owing to the rotating nozzle circular holes are formed,resulting in the most even distribution of tension possible in thecontainer wall in the area surrounding the hole.

In one embodiment of the invention, the nozzle-carrying arm is formedwith an internal channel for supply of the cutting medium, said armbeing designed with essentially right-angled bends. The reason thereforis that the pressurised medium contains or is admixed with an abrasiveto increase the cutting ability of the jet. In addition, the abrasiveconsiderably increases the friction on the nozzle and on other part ofthe system. In order to reduce the wear on the channel walls, the bondsin accordance with one embodiment are given an essentially right-angledconfiguration. Some of the abrasive will then settle as a protective bedbetween the channel wall and the pressurised cutting medium and in thismanner reduce the abrasive effects on the internal face of the channelwall.

To achieve a cutting effect on the above-enumerated objects that arerelevant for the intended purpose, the cutting medium should have apressure of 100-600 bars when leaving the nozzle. The flow rate of thecutting medium should be about 10-50 l/min through the nozzle.

An additional advantage gained by the invention is that the mosthazardous steps found in the prior-art technology either are eliminatedor may be carried out by personnel working at a safe distance from thecritical area. Once the tool is applied in abutment against a containerwall, it may be remote-controlled from a control centre located at asuitable distance from the hole-cutting area. The jet pressure and therate of flow through the nozzle, for example, may be controlled from theoperating centre according to one embodiment. Also the rotary motion ofthe nozzle above the container wall as also the supply of a correctamount of abrasive are remote-controlled. In this manner no human beingin the vicinity need be exposed to danger during the very hole-cuttingoperation.

The individual situation and other circumstances prevailing while acontainer of some kind need to be emptied obviously will govern theactual method, and the invention offers further possibilities to beimplemented according to need. Since evacuation will often be necessarywhenever pressurised, highly inflammable or combustible substances areinvolved, a particularly advantageous features of the tool is forinstance that it may comprise means to allow test pressurisation priorto initiation of the operation itself. This test pressurisation may alsobe controlled and the results be read from a control station situatedoutside he hazard area.

As regards the case described above, the safety outlet from the coverpreferably is provided with a closure device, such as a valve of somekind that could be subjected to checking. Also this closure devicepreferably is adjustable by means of remote control of some kind.

Should a container holding a poisonous medium need to be evacuated,without any risks of leakage, and the medium need to be transportedthrough some distance it is possible to employ for instance ahole-cutting tool not equipped with a controllable closure device in thearea of the safety outlet since in such a case pressure control is oflesser importance.

The cutting medium and the abrasive are chosen in consideration of thecontents of the container and their tendency of reaction to varioussubstances. Commonly used abrasives that may be employed in conjunctionwith the present invention are for example iron oxide, aluminium oxide,silica sand, garnet minerals and similar minerals. As regards hazardousgoods, official rules and regulations specify which substances may becombined.

Within the scope of the inventive idea, the various characterisingfeatures of a tool or a method of the kind defined above could of coursebe combined freely or exist as independent embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be further described in the following by way of oneembodiment and with reference to the accompanying drawings, wherein

FIG. 1 is a schematic view of an arrangement of means for cutting holesin a tank with a view to evacuate its contents.

FIG. 2 is a principle sketch showing the manner in which thehole-cutting tool is applied against a container wall.

FIG. 3 is an enlarged view of part of FIG. 2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

FIG. 1 illustrates schematically an arrangement of means for evacuationof the contents of a tank 20. A tank car 22, comprising a control centre25 for controlling a hole-cutting tool 1, is positioned at a pointspaced from the tank 20 concerned. The control of the hole-cutting tool1 may be effected by transfer of signals between the control centre 25and the hole-cutting device 1 wireless-fashion or via a cable 14.

In accordance with the preferred embodiment shown and described herein,the pressure source preferably is a motor-driven high-pressure pump 24.The motor could be a hydraulic motor, which in turn is powered by a pumpor an engine, not shown, such as a combustion engine. The motor as wellas the high-pressure pump 24 are of more or less conventional design andare installed in the tank car 22 shown in the drawing figure. Thecapacity of the high-pressure pump 24 is such as to enable it todischarge the pressurised medium at a pressure in the range of 100-300bars, preferably about 200 bars and a flow rate in the range of 10-50l/min, preferably about 40 l/min. In some applications the pressure ofthe cutting medium as it leaves the nozzle could, however, be as high asup to 600 bars, which shows that other embodiments are not restricted toonly the pressure interval of 100-300 bars. Also the flow rate couldexceed the value defined above, depending on the area of application,and could amount to more than 100 l/min.

Normally, the cutting medium 19 is ordinary water, to which preferablyis added one or several liquid and/or particulate additives to increasethe hole-cutting ability. One additive of this kind is an abrasive, suchas a blasting agent containing particles of iron, sand, or some otherabrasive substance that increases the speed of cutting through thecontainer wall. For cutting holes in a container wall made fromstainless steel aluminium oxide is advantageously used as the abrasive.Depending on the contents of the container to be evacuated, watersometimes is an unsuitable cutting medium 19 and in such cases it may bereplaced by for instance oil.

The equipment described above also comprises a vessel 26 containing thedescribed abrasive that is added to the cutting medium. Furthermore,FIG. 1 shows a flaring device 23, in which residual gases may becombusted after having been fed through a draw-off hose 16 from the tank20 that is being evacuated. In many cases, parts of the contents may beutilised and the inventive idea also covers the possibility of conveyingthe container contents through another draw-off hose 17 to anothercontainer, as illustrated in FIG. 1 by the tank of tank car 22.

FIG. 2 shows the tank 20 together with the hole-cutting tool 1 in itsposition mounted on the container wall 21. Summarily, it could bedescribed as a device to be placed around the cutting-tool proper andcomprising a cover 5 having a safety outlet 10 and sealing means 7,designed for sealed-off abutment, located at the cover end intended tobe applied against the container wall 21. In order to allow completelysealed-off abutment between the cover 5 and the container wall 21 thesealing means 7 ensuring sealed-off abutment may have a slightly curvedconfiguration at the base of the cover 5, corresponding to the curvaturedescribed by the radius of the container 20 concerned.

In a preferred embodiment, the sealing means 7 is made from some rubbermaterial. The sealing means could for instance be in the form of tworubber mouldings extending next to one another in spaced-apartrelationship around the lower face of the cover 5. The groove formedintermediate the rubber mouldings then forms a cavity from which, whenthe cover 5 abuts against the container wall 21, the air may beevacuated, for instance by means of a vacuum bell jar, not shown herein.The hole-cutting tool 1 may be fixed securely to the container wall 21by other methods than by vacuum. Other alternatives are by means ofstrapping, chains or wires, should the circumstances otherwise allowattachment of the hole-cutting tool 1 by such means. Other alternativesto vacuum are glue, magnets or, as a matter of fact welding, should thisbe considered reasonable in view of the situation otherwise. Thesevarious alternatives could of course be combined in various ways toprovide optimally sealed-off abutment conditions. The advantage of thismethod and tool is that it allows test pressurisation to be effectedbefore the very hole-cutting operation is initiated. Should a risk ofleakage still persist, silicon is applied between the seals.

From the safety outlet 10 extend one or several hoses, their numberdepending on how one chooses to distribute the contents being evacuated.According to one preferred embodiment of the invention an adjustableclosure device 15 is installed adjacent the safety outlet 10. Theclosure device 15 is adjustable between a completely closed position,not shown, wherein the device is closed tightly, also when exposed toconsiderable excess pressures of 10-20 bars or more, and an openposition, wherein the contents in the form of liquid or gas is allowedto flow out of the container.

In FIG. 3, the line 12 through which the cutting medium 19 is supplied,is coupled to the nozzle 2 via a rotary arm 4, which is formed withbends 27. The arm 4 is formed with an internal channel, through whichthe cutting medium 19 is supplied. The bends 27 are essentiallyright-angled in order to force some of the abrasive of the cuttingmedium to collect in the corners of the bends, where they remain in theform of a protective bed between the continuously supplied cuttingmedium 19 and the channel. Contrary to expectations, this configurationof the arm 4 imparts an increased serviceable life.

From the nozzle 2, the cutting medium 19 in the form of a jet is made toimpinge on the container wall 21 to sever the latter for thehole-cutting operation. Because the nozzle 2, which is supported by thearm 4 by means of a nozzle holder 3, is made to perform a rotarymovement about an axis (A) while at the same time the jet is beingdischarged through the nozzle, a hole of essentially circularconfiguration is eventually made in the container wall.

The cover 5, when assuming its mounted position, together with thecontainer wall 21 form a closed capsule around the nozzle 2. In order tofeed cutting medium 19 to the rotating arm 4 from the pipeline 12, thecutting medium 19 is passed through some kind of swivel means 18 and agasket 6. The purpose of the gasket 6 is to ensure that the supply tothe encapsulated nozzle 2 is effected without leakage. The arm 4 is madeto rotate about an axis (A) by a rotator, not shown, which via ahydraulic-motor connector 13, 14 is connected to a pressure source 24,such as a hydraulic motor.

As will be appreciated, the invention should not be consideredrestricted to the embodiment as shown and described but may be varied atliberty within the scope of protection as defined in the appendedclaims.

1. A tool for cutting holes in a container wall such as in a tank, acistern, a pipeline, a vehicle, a ship, a production line or the likethat contains inflammable, explosive, or other hazardous gases andliquids wherein the tool comprises means for pressurising a cuttingmedium and discharging said medium via a nozzle, in that at least thenozzle is arranged in an enclosing cover comprising a safety outlet forevacuation of the container contents, and having means for sealed-offabutment against the container wall concerned in the area in which holecutting is to be performed, said nozzle arranged to be directed towardsthe container wall in such a way that in use the cutting medium isdischarged in the form of a jet impinging against the container wallwith sufficient force to cut through said wall.
 2. A tool as claimed inclaim 1, said tool formed with an arm supporting the nozzle forrotational movement about an axis.
 3. A tool as claimed in claim 2,wherein said arm supporting the nozzle has an internal channel forsupply of the cutting medium, said arm being formed with essentiallyright-angled bends.
 4. A tool as claimed in claim 2, said toolcomprising an adjustable closure means arranged adjacent the safetyoutlet.
 5. A tool as claimed in claim 2, said tool arranged in such amanner as to ensure that the pressurised cutting medium has a pressureof 100-600 bars upon leaving the nozzle.
 6. A tool as claimed in claim2, said tool arranged in such a manner as to ensure that the cuttingmedium flow rate through the nozzle is in the range of 20-60 l/mm.
 7. Atool as claimed in claim 2, wherein at least the arm and the nozzle areremote-controlled from a control station located at a distance from thehole-cutting area.
 8. A tool as claimed in claim 1, wherein thepressurised cutting medium contains or is admixed with an abrasive.
 9. Atool as claimed in claim 1, said tool comprising an adjustable closuremeans arranged adjacent the safety outlet.
 10. A tool as claimed inclaim 1, said tool arranged in such a manner as to ensure that thepressurised cutting medium has a pressure of 100-600 bars upon leavingthe nozzle.
 11. A tool as claimed in claim 1, said tool arranged in sucha manner as to ensure that the cutting medium flow rate through thenozzle is in the range of 20-60 l/mm.
 12. A tool as claimed in claim 1,wherein at least the arm and the nozzle are remote-controlled from acontrol station located at a distance from the hole-cutting area. 13.The tool of claim 1, wherein the sealed-off abutment against thecontainer is static.
 14. A tool for cutting holes in a container wallsuch as in a tank, a cistern, a pipeline, a vehicle, a ship, aproduction line or the like that contains inflammable, explosive, orother hazardous gases and liquids wherein the tool comprises means forpressurising a cutting medium and discharging said medium via a nozzle,in that at least the nozzle is arranged in an enclosing cover comprisinga safety outlet for evacuation of the container contents, and havingmeans for sealed-off abutment against the container wall concerned inthe area in which hole cutting is to be performed, said nozzle arrangedto be directed towards the container wall in such a way that in use thecutting medium is discharged in the form of a jet impinging against thecontainer wall with sufficient force to cut through said wall, said toolformed with an arm supporting the nozzle for rotational movement aboutan axis, wherein said arm supporting the nozzle has an internal channelfor supply of the cutting medium, said arm being formed with essentiallyright-angled bends.